Question: $ E = \left[\begin{array}{rrr}2 & 0 & 1 \\ 2 & 2 & 2 \\ 1 & 1 & 2\end{array}\right]$ What is $ E^{-1}$ ?
$ = \left[\begin{array}{rrr}\frac{1}{2} & \frac{1}{4} & -\frac{1}{2} \\ -\frac{1}{2} & \frac{3}{4} & -\frac{1}{2} \\ 0 & -\frac{1}{2} & 1\end{array}\right]$